1. Field of the Invention
The present invention relates to a field emission display device and a field emission type backlight device, and more particularly, to a field emission display device and a field emission type backlight device in which a sealing structure for hermetically sealing a vacuum-exhausted panel space is provided as an exhaust path for an impure gas in the panel space.
2. Description of the Related Art
A field emission display device is a self-luminous display device that directly reproduces a full color image by concentrating a high electric field on an emitter that is an electron emission source to induce an emission of cold electrons and directing the electrons accelerated by a voltage difference between a cathode electrode and an anode electrode to collide with red, green, and blue phosphors. A field emission type backlight device is a backlight device that uses the aforementioned field emission, and does not form an image by itself but is mounted on a rear surface of a separate image-forming device, such as a liquid crystal display panel to supply a uniform surface light to the image-forming device.
In the field emission display device and the field emission type backlight device, a cathode substrate and an anode substrate are disposed facing each other and spaced apart from each other. A cathode electrode and a gate electrode crossing the cathode electrode are disposed on the cathode substrate, and the emitter, which is the electron emission source, is disposed at a crossing portion of the cathode electrode and the gate electrode. An anode electrode and a phosphor emitting a light by colliding with the electrons emitted from the electron emission source and accelerated by the anode electrode, are disposed on the anode substrate. The cathode substrate and the anode substrate are attached to each other by a sealant sealing a panel space therebetween. The panel space should be kept in a high vacuum state so as not to disturb the movement of the emitted electrons, and particularly to prevent charged particles from being generated by collision between an impure gas in the panel space and the accelerated electrons. Accordingly, a method for manufacturing the foregoing devices necessarily includes a vacuum exhaust process for sucking an impure gas, such as vapor, from the panel space with a vacuum pump and discharging the impure gas to the outside. According to the related art, an exhaust hole is perforated in a portion adjacent to an edge of the cathode substrate deviating from a display region, and an exhaust pipe is attached to a rear surface of the cathode substrate so as to communicate with the exhaust hole, and then the exhaust pipe is connected to the vacuum pump so that the impure gas in the panel is pumped out until the inside of the panel reaches a vacuum. In attaching the exhaust pipe, a frit paste is coated around the exhaust pipe located at the rear surface of the cathode substrate, and then the cathode substrate is heated to about the melting temperature of the frit paste in a heating chamber.
According to the related art, since the exhaust hole is perforated and the exhaust pipe is attached prior to the exhaust process, the number of processes increases. Also, when fine particles generated during the perforation of the exhaust hole through the panel, the particles may obstruct normal operation and result in a defective product. In addition, since the exhaust pipe is attached to protrude from a rear surface of the cathode substrate, the presence of the exhaust pipe restricts the amenability to reduce the thickness of the display device and to thereby manufacturing a thin type display device; moreover, the rear space of the display device occupied by the exhaust pipe is not suitable for use for another purpose, thus concomitantly decreasing space utilization.
Meanwhile, a portion adjacent to the edge of the cathode substrate is a region provided to perforate the exhaust hole, and thus cannot be used as an effective display region where a visual video image is displayed. Therefore, according to the related art, an ineffective region is necessarily generated due to the necessity for a perforation of the exhaust hole.
An impure gas generally remains in the panel space after the vacuum exhaust process. Therefore, a getter material that reacts well with an impure gas is injected into the panel, and is activated. The activated getter adsorbs the impure gas in the panel, and induces an internal space to a high vacuous state. According to the related art, the getter is dispersedly disposed in the exhaust pipe or an empty space in the panel except for a display region where electrodes are arranged. At this point, since the getter is exposed to an emission space of electron beams, a portion of electrons emitted from an emitter may be distorted in an unexpected path by interacting with the getter material. Also, since the getter after absorbing the impure gas becomes useless but still remains in the panel, a blank space for carrying the getter is separately required, and a separate supporting structure for fixedly supporting the getter is required. Consequently, according to the related art, the panel structure is complicated, and the degree of freedom of the design is restricted in the intensively designed panel structure.